Structural uniformity improvements by control of extra side facets in MBE growth of InP-based InGaAs ridge quantum wires

Using SEM, AFM and PL techniques, the origin of wire inhomogeneity and possible methods to improve the wire uniformity were investigated for the InP-based InGaAs ridge quantum wires formed by selective MBE growth on InP mesa-stripes. Appearance of extra side facets on [111]A sidewalls was found to be the major reason for horizontal and vertical waving of the ridge, leading to the inhomogeneity of the wire. High temperature growth of InGaAs buffer layer as well as intentional introduction of the misorientation into the mesa-direction were found to be significantly effective for reducing the width of the extra facets, resulting in the large improvement of the uniformity of the InGaAs ridge wire. Judging from the narrow PL FWHM of the InGaAs ridge quantum wire obtained with the present extra side facet control, the present wire possesses the best uniformity of all the InP-based InGaAs quantum wires reported so far. It also seems to have comparable or better uniformity than the GaAs-based quantum wires reported so far.